1. Field of the Invention
The present invention relates to an image processing apparatus and method, more specifically, generation of a normal map for preview.
2. Description of the Related Art
When printing an image, the color appearance may largely change between printing paper sheets to be used for printing. The factors that change the color appearance include the gloss of a printing paper sheet, and the color difference between printing paper sheets. Bumpiness on the surface of a printing paper sheet is also a large factor. For example, the color appearance of a printed image largely changes between printing paper (e.g., glossy paper) having a smooth surface and half-glossy paper (to be referred to as matte finished paper hereinafter) having bumpiness formed by matte finish.
On the other hand, computer graphics (to be referred to as CG hereinafter) uses a bump mapping method to express bumpiness on an object surface. This technique virtually expresses bumpiness on an object surface by tilting, in an arbitrary direction, a normal vector which determines the reflecting direction of light incident on the object surface. The use of the normal vector allows reproduction of the bumpiness on the surface of matte finished paper. Applying the CG technique to print preview enables more real print preview.
To use the bump mapping method, a normal vector map (to be referred to as a normal map hereinafter) which bitmaps a bundle of normal vectors is necessary. As normal map generation methods, techniques using a dedicated device are disclosed. In these techniques, bumpiness on an object surface is read by a dedicated device, thereby generating a normal map.
In the above-described methods using a dedicated device, the dedicated device itself is expensive, and its method of use is special. This makes it difficult to introduce the techniques.